Background: Researching falls in persons with ID is limited by difficulties in applying standardised balance outcome measures. The modified Gait Abnormality Rating Scale (GARS-M), developed to identify falls risk in older adults, requires only that the participant walks and thus may be a feasible falls research tool to use with people with ID. In the present study, we consider the interrater reliability of the GARS-M. Method: Nine people with ID were videotaped walking. These recordings were used by 10 physiotherapists to rate the person's walking on the 7 categories of the GARS-M. The intraclass correlation coefficient (ICC) was calculated for the physiotherapists' scores in each category and the total score; ICC [greater than or equal to] 0.7 indicating good interrater reliability. Results: The ICC was greater than 0.7 in only one category of the GARS-M, but ICC = 0.85 for the total score. Average time to rate one person was 8 minutes. Conclusions: The GARS-M is potentially useful for falls prevention research with people with ID. (Contains 4 tables.)